How to deal with a difficult person?

[Venannai]

Hopefully this I can get an answer on here because I feel stuck. A former friend and I had a falling out back in August. We did try to reconcile, but he would get mad when I talked to and hang out with other people more that I did him. I guess he wanted everything to return to how it was before the falling out, (which consisted more so of me being his clubbing buddy although I don't like clubbing, doing whatever he asked of me which I told him that I was not doing anymore, and him talking to me about his problems which he made clear that he don't want to happen anymore.) I kept to my word and made the changes that we talked about, but he still wanted EVERYTHING the exact same way (this is including what he said he wanted to happen on his end). By then, I took up doing other things that I wanted to do and started doing better in my classes, both of which I was not giving up for him. We eventually stopped talking, except he's a part of a academic program that I work at. There have been times where he would come into the office and would belittle me in front of the people that I'm talking to. There was also an instance on Instagram where I congratulated a mutual friend on their post and he immediately follows up with a comment along the lines of "I care for you more than she does, you know that right?!" After that I blocked him on Instagram and FB, but apparently the blocking feature doesn't work for IG if you have mutual friends. As for the situation at work, I tried to bring the matter of to my boss, but she ended up shaking me off.

I don't know if there is a right way to handle this situation, but I'm tired of the passive aggressiveness. Any advice would be appreciated.